The two high-profile Republicans are longtime friends, despite having campaigned against each other in the GOP primaries in which McCain ultimately prevailed. When Giuliani bowed out of the race, he immediately endorsed McCain.

Could Giuliani, who moonlights as the No. 1 Yankee fan, become the No. 2 on the Republican ticket?

"You hear all kinds of stuff, but I'm not thinking about anything but helping to get him elected," Giuliani said. "Beyond the fact that he's the candidate of my party, he's a very good friend."